Provided are systems and methods that relate to inspection of wellbore conduits and, more particularly to the detection and monitoring of defects in wellbore conduits using a distributed sensor system and a wireline transmitter.
A common problem associated with subterranean wells may be the corrosion of conduits and other downhole equipment in the wellbore. The expense of repairing and replacing the damaged equipment may be high. Conduits that may be susceptible to corrosion may include casing, production tubing, and other downhole equipment. Examples of common types of corrosion that may occur in a wellbore include, but are not limited to, the rusting of metal, the dissolution of a metal in an acidic solution, and patina development on the surface of a metal.
Early detection of corrosion in conduits and other downhole equipment may be important to ensure the integrity and safety of the well. Techniques that have been deployed for downhole corrosion detection may involve running corrosion monitoring logging tools in the production tubing. Different types of corrosion monitoring logging tools may include mechanical calipers, ultrasonic acoustic tools, cameras, electromagnetic flux leakage, and electromagnetic induction tools. However, the ability of these tools to detect corrosion in outer casing beyond that which the logging tool is run may be limited. Electromagnetic induction tools that include at least one transmitting coil and at least one receiving coil may be able to detect corrosion in the outer casing. The transmitting coil may induce eddy currents inside the casings, including the inner and outer casing, and the receiving coil may record secondary fields generated from the casings. Those secondary fields bear information about the electrical properties and metal content of the casings and may be inverted for any corrosion loss in the metal content of the casings. Electromagnetic induction tools may be frequency domain tools that operate at discrete set of frequencies (e.g., higher frequencies to inspect inner casings) and lower frequencies to inspect outer conduits). Alternatively, the electromagnetic induction tools may operate in the time domain by transmitting transient pulses and measuring the decay response versus time (e.g., earlier time may correspond to inner casing and later time may correspond to outer casing). Two-dimensional (axial and azimuthal) thickness image of the inner casing may be possible by loading the tool with multiple sensing pads that may be pressed again the inner wall of the production tubing. However, while these techniques may be used for corrosion monitoring, there may be drawbacks. For instance, most of these techniques may use a wireline truck and a crew and may also require production to be stopped during inspection operations. Since inspection may be performed multiple times during the life of a well, each wireline inspection operation may result in signification costs associated with it.